Einstein laid the theoretical foundations for lasers in 1917, and it took over 40 years of "impractical" scientific work before the first functioning laser was built. It took decades more for them to become a cheap, ubiquitous technological building-block. The research is still continuing, and there's no reason to assume it will stop eventually bearing fruit (for the societies that haven't decimated their scientific workforce, anyways). Look at the insanity required to design and build the EUV lasers in ASML's machines, which were used to fabricate the CPU I'm using right now, over a century after Einstein first scribbled down those obscure equations!
I sincerely wonder how someone that is unaware of any of this finds their way onto HN, but at the same time it is an educational opportunity. 'nothing practical' indeed...
What's interesting is how many things can be made to lase, and how many ways there are to do it. The list appears to be never ending and new entries are made all the time.
